Ketol-acid reductoisomerase
In enzymology, a ketol-acid reductoisomerase (EC 1.1.1.86) is an enzyme that catalyzes the chemical reaction
- (R)-2,3-dihydroxy-3-methylbutanoate + NADP+ (S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H+
| ketol-acid reductoisomerase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 Ketol-acid reductoisomerase tetramer, Alicyclobacillus acidocaldarius | |||||||||
| Identifiers | |||||||||
| EC number | 1.1.1.86 | ||||||||
| CAS number | 9075-02-9 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
Thus, the two substrates of this enzyme are (R)-2,3-dihydroxy-3-methylbutanoate and NADP+, whereas its 3 products are (S)-2-hydroxy-2-methyl-3-oxobutanoate, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (R)-2,3-dihydroxy-3-methylbutanoate:NADP+ oxidoreductase (isomerizing). Other names in common use include dihydroxyisovalerate dehydrogenase (isomerizing), acetohydroxy acid isomeroreductase, ketol acid reductoisomerase, alpha-keto-beta-hydroxylacyl reductoisomerase, 2-hydroxy-3-keto acid reductoisomerase, acetohydroxy acid reductoisomerase, acetolactate reductoisomerase, dihydroxyisovalerate (isomerizing) dehydrogenase, isomeroreductase, and reductoisomerase. This enzyme participates in valine, leucine and isoleucine biosynthesis and pantothenate and coa biosynthesis.
Structural studies
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes 1NP3, 1QMG, 1YRL, and 1YVE.
References
- Arfin SM, Umbarger HE (1969). "Purification and properties of the acetohydroxy acid isomeroreductase of Salmonella typhimurium". J. Biol. Chem. 244 (5): 1118–27. PMID 4388025.
- Hill RK, Sawada S, Arfin SM (1979). "Stereochemistry of valine and isoleucine biosynthesis. IV Synthesis, configuration, and enzymatic specificity of alpha-acetolactate and alpha-aceto-alpha-hydroxybutyrate". Bioorg. Chem. 8 (2): 175–189. doi:10.1016/0045-2068(79)90003-8.
- Kiritani K, Narise S, Wagner RP (1966). "The reductoisomerase of Neurospora crassa". J. Biol. Chem. 241: 2047–2051.
- Satyanarayana T, Radhakrishnan AN (1965). "Biosynthesis of valine and isoleucine in plants. 3. Reductoisomerase of Phaseolus radiatus". Biochim. Biophys. Acta. 110 (2): 380–8. doi:10.1016/s0926-6593(65)80045-5. PMID 5866387.